Diabetes Insipidus

Introduction

Diabetes Insipidus (DI) is a body water balance disorder. DI, also called “water diabetes,” is not the same type of diabetes as “sugar diabetes,” or Type 1 Diabetes, Type 2 Diabetes, or Gestational Diabetes. The diseases resemble each other because both have similar symptoms of increased urination and increased thirst. Other than that, the diseases are completely unrelated. They have different causes and treatments.

DI is an uncommon condition. It occurs when the brain does not produce enough antidiuretic hormone (ADH) or when the ADH does not work with the kidneys like it should. As a result, people with DI can experience excessive urination, fluid intake, and thirst. If treated, severe complications and a reduced life expectancy may be avoided.

Your body continually works to keep your body fluids balanced. When fluid volumes need to increase, your body signals you to be thirsty. In turn, you consume more fluids.

At certain times, urine production may need to decrease and the reabsorption of fluids may need to increase. This may occur when your blood volume is low, or when concentrations of blood sodium or other metabolites are high. Antidiuretic hormone (ADH), also called vasopressin, directs the rate of urine excretion. ADH is produced in the hypothalamus in your brain. ADH is stored and released into your bloodstream from a nearby structure, your pituitary gland. Once in the bloodstream, ADH travels to the kidneys. ADH directs the kidneys to decrease the production of urine by increasing the amount of water that is returned to the bloodstream.

Causes

DI occurs when the kidney’s system for balancing body fluids is disrupted. There are four types of DI. Each type has it own cause and treatment. The types include Central DI, Nephrogenic DI, Dipsogenic DI, and Gestational DI.

Central DI, also known as Pituitary DI or Neurogenic DI, results in a lack of ADH production. Central DI is caused by damage to the pituitary gland or the hypothalamus. The damage can occur from neurosurgery, infection, diseases, brain injury, tumor, or genetic disorders.

With Nephrogenic DI the kidneys do not respond to ADH like they should. As a result, the kidneys do not return fluids back to the bloodstream. Nephrogenic DI can be caused by kidney disease, sickle cell disease, kidney failure, and certain drugs. Nephrogenic DI can be an inherited disorder, particularly in male children that inherit an abnormal gene from their mother. In some cases of Nephrogenic DI, the cause is not known.

Dipsogenic DI is caused by damage to the thirst mechanism located in the hypothalamus. People with Dipsogenic DI experience an abnormal increase in thirst. The excessive fluid intake suppresses ADH secretion. It also increases the amount of urine output, resulting in excess urination at night or bedwetting. Further, water intoxication can occur. Water intoxication is a condition that lowers the amount of sodium in the blood and can cause brain damage.

Gestational DI can develop in some women during pregnancy. The placenta, which supports the baby, exchanges nutrients and waste products with the mother to help the baby develop. Gestational DI results when an enzyme produced by the placenta destroys the ADH in the mother. In rare cases, an abnormality in the thirst mechanism causes Gestational DI. Gestational DI often resolves four to six weeks after pregnancy, but can develop again in future pregnancies.

Symptoms

Symptoms of DI include excessive thirst, fluid intake, and urination. You may feel extremely thirsty even though you are drinking large amounts of fluids. You may even crave ice water. You may expel large amounts of urine. Ask your doctor how much is too much for you. You may also experience nocturia, the frequent need to urinate during the night, or bedwetting.

Diagnosis

Your doctor can diagnose the type of DI that you have. Tell your doctor your symptoms and medical history. Your doctor may measure your urine output by having you collect your urine in a special container for a period of time. Your doctor will also conduct a series of tests, including a urinalysis, a fluid deprivation test, and in some cases, a Magnetic Resonance Imaging (MRI) scan of your brain.

The urinalysis is an examination of your urine sample. People with DI have low concentrations of sodium and waste products. Their urine also has a high amount of water.

A fluid deprivation test is used to help identify the cause of the DI. The fluid deprivation test can determine if the DI is caused by excessive fluid intake, abnormal ADH production, or a problem in the way that the kidney responds to ADH. For the test, you will not drink fluids for a period of time. Your doctor will measure changes in your body weight, your urine output, and your urine composition.

Your doctor may order a MRI scan to provide a very detailed view of your brain structures. This can help your doctor identify any problems with your pituitary gland or hypothalamus.

Treatment

Your doctor will treat the underlying cause of your condition, if possible, and your symptoms of DI.
The goal of treatment is to regulate the water balance in your body. This may be achieved in different ways, depending on the type of DI that you have.

Central DI and most cases of Gestational DI may be treated with a synthetic “created” hormone called desmopressin. Desmopressin is used to treat ADH deficiency. It can be taken by injection, nasal spray, or a pill. You should drink fluids only when you are thirsty and not at other times while you are taking desmopression. Cases of Gestational DI that are caused by a thirst mechanism impairment should not be treated with desmopressin. Nephrogenic DI and Dipsogenic DI cannot be treated with desmopressin. However, medications can treat some of the symptoms. People with Nephrogenic DI may need to follow a low sodium or low protein diet.

Am I at Risk

Certain underlying conditions are associated with the development of DI. However, people with an underlying cause of DI may never develop the disease. You should tell your doctor about your medical history and discuss your concerns.

Overall, underlying conditions associated with DI include injury to the pituitary gland or the hypothalamus in the brain. Such conditions include neurosurgery, infection, diseases, brain injury, tumor, or genetic disorders. Certain medications can cause DI. Such medications include lithium, amphotericin B, and demeclocycline. Additionally, Gestational DI can develop in women during pregnancy.

Complications

Dipsogenic DI can lead to water intoxication. Excessive water in the blood stream can cause low sodium levels in the blood and suppressed ADH production, resulting in a condition called hyponatremia. In severe cases, people can develop water intoxication. Water intoxication is very dangerous. Symptoms of water intoxication include shortness of breath, headache, confusion, loss of appetite, feeling tired all of the time, and nausea. It can lead to seizures, coma, and death.

Inadequate fluid consumption can result in dehydration and electrolyte imbalance. Symptoms of dehydration include dry skin, dry mouth, sunken appearing eyes, fever, rapid heart rate, and unintentional weight loss. Severe dehydration can lead to shock. Electrolytes are compounds that help to maintain body metabolism and function. Symptoms of an electrolyte imbalance include feeling tired all of the time, headache, irritability, and muscle pains.

This information is intended for educational and informational purposes only. It should not be used in place of an individual consultation or examination or replace the advice of your health care professional and should not be relied upon to determine diagnosis or course of treatment.

The iHealthSpot patient education library was written collaboratively by the iHealthSpot editorial team which includes Senior Medical Authors Dr. Mary Car-Blanchard, OTD/OTR/L and Valerie K. Clark, and the following editorial advisors: Steve Meadows, MD, Ernie F. Soto, DDS, Ronald J. Glatzer, MD, Jonathan Rosenberg, MD, Christopher M. Nolte, MD, David Applebaum, MD, Jonathan M. Tarrash, MD, and Paula Soto, RN/BSN. This content complies with the HONcode standard for trustworthy health information. The library commenced development on September 1, 2005 with the latest update/addition on April 13th, 2016. For information on iHealthSpot’s other services including medical website design, visit www.iHealthSpot.com.